This invention relates to an apparatus for cleaning liquids and, more particularly, for cleaning liquids which themselves simultaneously are being used to clean the surfaces of difficult-to-clean objects such as contaminated air filters from commerical-size air-conditioning systems.
With the advent of twentieth century comfort living and the onset of air pollution standards, the installation and utilization in commercial and even private establishments such as apartment buildings, of air conditioning equipment has proliferated. Governmental control for safety purposes, furthermore, have become stricter with respect to removal of flamable, hazardous substances from exhaust fumes of units vented traditionally to the outside environment such as the exhaust fumes from ovens, stoves, grills and deep-fat fryers of restaurants. For economy purposes. the vast majority of units designed for commerical-sized air conditioning units and exhaust conditioning units are designed for use with replaceable permanent filters of the gas stream to be conditioned. Such permanent filters are constructed of the wide range of materials including for example aluminum, stainless steel, fiber glass, and other ceramics. In actual use, while the permanance of such filter elements has satisfied one basic economy requirement, for example, problems have arisen due to the fact that such filter elements periodically must be cleaned. This cleaning requirement is aggravated in practice by the nature of the contamination deposit build-up on the surfaces of cleaning elements by the combination of inorganic and organic solid particles and liquid droplets normally encountered over even relatively short periods of time, and the further human tendancey not to attend to the necessary removal and cleaning of such filtering elements until the contamination of dirt, dust and grime reaches such levels that the filtering capacity of the units is impaired.
Accordingly, an increasing need exists for suitable techniques for cleaning such filtering elements in an efficient relatively inexpensive manner. Cleaning techniques heretofore suggested for use in removing contaminants from such filtering elements, however, generally have not been even approaching being tolerable. Suggestions to employ conventional detergents have not been satisfactory due to the nature of the dust, grease, and grime contamination characteristically found on and in filters used in commercial air-conditioning and exhaust systems, nor has the use of such conventional detergents with a combined use of mechanically applied abrasion proved successful, since such proposed approaches do not achieve cleaning of the interior of a fouled filtering element. Most techniques previously suggested for cleaning such filtering elements, therefore, have had to resort to the use of harsh solvent liquids and solutions which attack organic matter, with the obvious serious drawback of presenting a safety problem to the operator handling such filtering elements in the cleaning equipment employed, as well as to the environment of the cleaning equipment of itself. Such prior techniques, moreover, due to their characteristic disadvantages, have proven in practice to be useful only in achieving batch, wise operation.
Accordingly, the search has continued in the prior art for the development of a technique which is capable of efficiently and economically achieving removal of contaminants from filtering units conventionally employed in commercial air-conditioning and venting systems, and further capable of accomplishing such contaminant removal using conventional detergents which are non-harmful to human contact and adapted to attain such result in an essentially continually operating system.